1. What It Is and Why You Need It

\n Crow is a lightweight, fast, and modern micro web framework for the C++ language, inspired by the popular Python framework Flask. It is designed for creating REST APIs, web services, and simple web applications with minimal code and without the need for complex configuration. Crow is written in C++17/20 and uses the asio (or boost.asio) libraries for asynchronous request handling, making it one of the most performant solutions in its niche.\n

\n Why use Crow? If you need to quickly deploy an HTTP server in C++ for processing JSON requests, serving static files, or creating a microservice, Crow is the ideal choice. Unlike heavyweight frameworks like drogon or pistache, Crow has a minimal footprint, a simple API, and does not require code generation or complex macros. It is well-suited for embedded systems, IoT devices, game servers, and any scenario where speed and low memory consumption are important.\n

\n Crow supports routing (including dynamic URL parameters), middleware, JSON handling (via a built-in library or nlohmann/json), WebSocket, CORS, multipart/form-data, and much more. The framework is actively developed, has good documentation, and a stable community.\n

2. Installation

Crow is a header-only library (in most cases), so installation boils down to cloning the repository and including the header files. However, it is recommended to use CMake for building examples and projects.

Method 1: Cloning (recommended for development)

git clone https://github.com/CrowCpp/Crow.git\ncd Crow\nmkdir build\ncd build\ncmake ..\nmake\nsudo make install

Method 2: Using vcpkg

vcpkg install crow

Method 3: Integration via CMake FetchContent

include(FetchContent)\nFetchContent_Declare(\n    crow\n    GIT_REPOSITORY https://github.com/CrowCpp/Crow.git\n    GIT_TAG v1.0.0\n)\nFetchContent_MakeAvailable(crow)\n\ntarget_link_libraries(your_project PRIVATE Crow::Crow)

Important: Crow requires a compiler with C++17 support (gcc 8+, clang 7+, MSVC 2019+). The asio (or boost.asio) library is also required. If you use vcpkg, dependencies will be pulled in automatically.

3. Quick Start — Minimal Working Example

Create a file main.cpp with the following content:

#include "crow.h"\n\nint main() {\n    crow::SimpleApp app;\n\n    // Define a route for the root URL\n    CROW_ROUTE(app, "/")([](){\n        return "Hello, Crow!";\n    });\n\n    // Start the server on port 8080\n    app.port(8080).multithreaded().run();\n}

Compile and run:

g++ -std=c++17 -pthread main.cpp -o crow_server\n./crow_server

Open your browser and navigate to http://localhost:8080. You will see a welcome message.

4. Main Methods/Functions/Classes

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